cell_solid and feet_blocked go, and so does the prediction in the player's
movementlogicfunc. That prediction was only ever exact because the town has zero
gravity and zero drag -- v is t, so `x + tx * dt` is where the step lands. A map
with gravity would have had to fold ey in as well, which is the game
re-implementing the integrator. Resolution runs after the move now, so there is
nothing to predict.
The map's decoration layer carries `collidable`, which retires JRPG_LAYER_SOLID:
akgl_TilemapLayer has no name member, so the game and the map had to agree on an
index out of band and inserting a layer in Tiled broke it.
The edge of the world is not on any layer, so it is four static proxies covering
the outer ring plus a tile of overhang -- one pool slot per side instead of a
hundred solid tiles, and the first use of the static-proxy path in either
example. They carry LAYER_STATIC explicitly: shape_box defaults a shape to
LAYER_ACTOR, and a wall left on that layer is a wall everything walks through.
Only the player gets a shape. NPCs stand still and are spoken to; the follower
is a child snapped to its parent every step.
Verified against the old implementation with the demo script rewritten to hold
one direction: holding left into a building stops the player at x=122 with both,
and holding up into the map's edge stops them at y=-4 with both.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KzBDV2fqgnUAcqCKqKvc71
collision.c was 383 lines that re-implemented akgl_physics_simulate's own
arithmetic, because movementlogicfunc runs before gravity, drag and the move
and so had to predict where the actor would end up. The whole file goes. What
replaces it is three lines in main.c, a shape on the player and the blob, and a
`collidable` property on the map's terrain layer -- which also retires
SS_TERRAIN_LAYER_ID, a compiled-in layer id that broke whenever somebody
reordered layers in Tiled.
grounded stays a probe rather than becoming a contact test. A contact says
something pushed back this step; grounded asks whether there is a floor to push
off, and that stays true through the frame after landing. The blob keeps its own
wall and ledge probes for the same reason: the resolver does not say which side
of the blob it was pushed from, and says nothing at all about a floor that is
missing.
The summary line now carries the player's resting position, because exiting 0
was not evidence that collision ran. It reports 136.0,160.0 grounded after 240
autoplay frames -- feet at y=192, flush on the surface of terrain row 12.
The tutorial's collision section is rewritten around the library's, keeping the
quarter-of-a-pixel story as what a predicting resolver costs. The docs harness
learns `json excerpt=`, so the map property the chapter quotes is checked
against the map.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KzBDV2fqgnUAcqCKqKvc71
The sidescroller's controls did nothing. `akgl_controller_handle_event` matched
`event->key.which == curmap->kbid` exactly, with no way to say "whatever
keyboard the player is typing on", so the game did the obvious thing and bound
`SDL_GetKeyboards()[0]`.
That cannot work. The id a key event *carries* is chosen by the video backend
and is not required to be an id `SDL_GetKeyboards()` reports. On X11 without
XInput2 every key event carries `SDL_GLOBAL_KEYBOARD_ID`, which is 0, while
`SDL_AddKeyboard` registers the attached keyboard as `SDL_DEFAULT_KEYBOARD_ID`,
which is 1; with XInput2 the events carry the physical slave device's
`sourceid` while `SDL_GetKeyboards()[0]` may be the master. Either way the map
matched nothing and every key press was dropped.
A `kbid` or `jsid` of 0 now matches any device of that kind. 0 is safe to spend:
SDL documents `which` as 0 when the source is unknown or virtual, and joystick
ids start at 1, so no real device is 0. A non-zero id still matches only that
device, which is what keeps two local players on two keyboards apart, and there
is a test for that half too. `util/charviewer.c` already passed 0 and depended
on the old behaviour by accident; it works under XInput2 now as well.
Two reasons this shipped, both closed:
- Every test in tests/controller.c dispatched an event whose id equalled the id
the map was bound with, so none of them could see it.
- The sidescroller's smoke test called the control handlers directly instead of
dispatching events, so it passed against a control map that matched nothing.
It now pushes synthetic events through akgl_controller_handle_event from a
deliberately non-zero device id and fails if the press does not arrive.
Verified by breaking the binding and watching the run exit non-zero.
`test_controller_wildcard_device_ids` was written first and failed against the
unfixed library with "a map bound to keyboard 0 ignored a key press from device
11", which is the whole reason to trust it now that it passes.
The controls were documented, in one sentence. Chapter 19 has a proper table of
them, and chapter 15 explains why not to reach for SDL_GetKeyboards(). The
header said the match was exact and now says what it does.
Co-Authored-By: Claude Code <noreply@anthropic.com>
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
examples/sidescroller and examples/jrpg are complete programs, built with the
library and exercised headless by ctest. The chapters quote them with
`c excerpt=examples/...` blocks rather than restating the code, so a chapter
cannot drift from a program that compiles -- the excerpt check fails the moment
the source moves. 34 excerpts in one chapter, 21 in the other.
The two are complementary. The sidescroller is the physics tutorial: gravity, a
jump, coins, hazards. The JRPG is the content-pipeline tutorial: a town map,
NPCs spawned from map objects, four-way per-facing animation, a text box, a
follower.
Both smoke tests drive real SDL_Events through akgl_controller_handle_event and
step the physics clock at a fixed 1/60s rather than sleeping, so a scripted run
is deterministic and finishes in under five seconds.
Writing them is what turned up most of the defects recorded in the next commit,
because a game exercises paths a unit test does not. Each workaround says in the
chapter which library gap forced it:
- collision is written in a custom movementlogicfunc, because
akgl_physics_arcade_collide raises AKERR_API and akgl_physics_simulate never
calls collide at all;
- the sidescroller cancels the step's own gravity when it blocks downward,
because otherwise a quarter-pixel of penetration makes the *horizontal* sweep
report blocked and the character walks backwards a tile at a time;
- both clear movement_controls_face on every map-spawned actor, because the
default facefunc leaves a stopped actor with no facing bit, no sprite, and no
draw;
- the JRPG's follower gets a renderfunc that nulls obj->parent for the duration
of the draw, because a child's offset is counted twice.
Assets are CC0 from three Kenney packs, vendored with per-pack licence text,
per-file provenance, and the geometry contract in
docs/tutorials/assets/README.md. CC0 specifically rather than merely free: a
reader who copies a tutorial into their own game inherits no obligation.
scripts/fetch_tutorial_assets.sh refreshes them in the shape
mkcontrollermappings.sh was fixed into for 0.5.0 -- it checks curl's status,
refuses a pack page that does not say CC0, verifies the archive and the staged
dimensions, and leaves the tracked bytes untouched on any failure. Both failure
paths were tested, and a no-op refresh is byte-identical.
Co-Authored-By: Claude Code <noreply@anthropic.com>
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
libakgl exports 157 functions and the only user-facing documentation was a FAQ
in README.md whose examples did not compile: two unbalanced `PASS()` calls, a
`sprite->frameids = [0, 1, 2, 3];` that is not C in any dialect, a stray `9`
inside a bitmask expression, an `int screenwidth = NULL`, and -- in the first
snippet a reader ever saw -- the exact `strncpy` call AGENTS.md forbids.
That is not a reader routing around typos. It is what happens to samples that
nothing executes. This is akbasic's documentation harness with the interpreter
taken out and the ability to link and run put in.
The contract is a set of fence info strings, so an example is ordinary markdown
that still highlights on the forge:
```c compiled with -fsyntax-only -Wall -Werror
```c wrap=NAME the same, wrapped in tests/docs_preludes/NAME.pre/.post
```c run=NAME linked against akgl and run headless
```c excerpt=PATH must still appear verbatim in PATH
```c screenshot=NAME also the source of docs/images/NAME.png
```json kind=KIND loaded through the real akgl_*_load_json
```output the exact stdout of the runnable block above it
`run=` is why this links at all: -fsyntax-only proves a call typechecks, not
that the startup order works or that an ATTEMPT block gives back what it took.
`json kind=` exists because the asset formats are documented in prose and read
by four loaders with nothing tying the two together -- util/assets/littleguy.json
is already invalid against the loader it ships with.
A fence with no info string is a hard error, and so is an unknown one. The
failure mode this exists to prevent is passing because it quietly ran nothing,
so an unannotated block is a missing decision rather than a default. Exit status
is the number of failed examples; 2 for a usage error, which is a different
thing and has to be distinguishable.
Proven to fail on all ten of its failure modes -- untagged fence, non-compiling
snippet, stale excerpt, orphan output block, unknown info string, run= output
mismatch, invalid JSON, missing figure, a -Werror warning, and a dangling
preload= -- because a check that has never failed has not been tested.
`-Werror` here although AKGL_WERROR stays off for the library: that option is
off so a new compiler's diagnostic cannot break a consumer's build, and a doc
snippet is not a consumer. A sample that warns is a sample that teaches the
warning.
Registered as `docs_examples` and `docs_screenshots`. No docs-path filter in CI,
deliberately: documentation goes stale because the code moved, not because
somebody edited a chapter.
Co-Authored-By: Claude Code <noreply@anthropic.com>
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
